What happened
On February 28, 1998, a Piper PA 32 RT-300 T, registration N-104FX, departed Courchevel for a VFR flight to Lyon Bron. Shortly after takeoff, the aircraft departed from the established flight path. While the prescribed route required a left turn into the Bozel valley to reach Moutiers, the pilot instead continued straight toward the Pas des Brebis pass.
At approximately 10:40 UTC, the aircraft struck the terrain at an altitude of 2,420 meters, roughly 20 meters below the ridge line. The impact occurred on a strip of earth at the edge of a snow-covered area. The collision resulted in two fatalities, as both the pilot and the passenger were killed upon impact. The aircraft was destroyed.
The investigation
The investigation focused on the pilot's decision-making, the meteorological conditions, and the aircraft's mechanical state. Investigators examined the engine and turbocharger, finding that while the engine was delivering power at impact, the turbocharger was suffering from pre-existing damage, including a crack and internal interference that reduced its efficiency.
Meteorological analysis revealed that while the sky at Courchevel was clear, a layer of stratocumulus clouds was progressively filling the Bozel valley. The investigation also considered the optical phenomenon of "whiteout" (jour blanc), where a lack of contrast between the snowy ground and the sky makes it difficult to perceive depth and distance.
Findings
- The primary cause of the accident was the pilot's decision to continue toward the mountain pass despite lacking the visual references necessary to confirm the pass could be cleared.
- The pilot's limited experience in mountain flying contributed to the decision to avoid the Bozel valley, which was filling with clouds, in favor of a direct path toward the ridge.
- The poor evaluation of the environment was exacerbated by the whiteout phenomenon, which likely obscured the pilot's ability to judge the distance to the ridge.
- A degraded turbocharger performance reduced the aircraft's climb rate, making the direct crossing of the pass more difficult than the pilot may have anticipated.